Probably of humble origins in one of the Illyrician provinces of the Empire[a] he was one of the group of men from this region who chose a military career – or had it chosen for them – whose professional capabilities brought them to the fore of public life in those troubled times.
The evidence suggests that he earned the trust of the Emperors Gallienus and Claudius II and, possibly, Marcus Aurelius Probus among their successors and that he was one of the principal commanders in the prolonged war against a coalition of what the late antique Greek writers called Scythian peoples whose incursions in that period seemed to threaten the very survival of the Roman state.
It was at one time believed that Marcianus was to be identified with the Marianus who was one of three leaders mentioned in a recently discovered fragment of Dexippus as coordinating Greek resistance to a Gothic invasion that swept across the Balkans in the early 260s.
[5] Gerov wrote before recent archaeological and numismatic discoveries encouraged the development of a new view of Imperial activity in Asia during the reign of Claudius II and Marcianus's possible involvement in this.
[7] Thus his biography did not consider the possibility that Marcianus commanded an expedition to counter Scythian incursions into Asia region at this time, for which the only literary reference was an off-hand statement in Zosimus.
Discovered in Rhodes, but originally from Kibyra, Pamphylia (ancient city in south-west Turkey, near the town of Gölhisar, in Burdur Province: This inscription (in Greek) was on a monument honouring one "Aurelius Marcianus", who is celebrated as "a most generous military leader".
That all three dedicatees mentioned in these inscriptions not only bore the same cognomen (and in the Asian instances, the same gentilicium), but were also of this rank strengthens the proposition that they were, in fact, the same man who was also the Marcianus referred to by the SHA and Zosimus.
In that latter connection, a recent study of a fourth inscription from the ancient city of Sagalassos (Lycia et Pamphylia – modern Antalya province, Turkey) seems to throw further light on his career.
The only literary reference is from Zosimus who, recording Marcianus's appointment as theatre-commander in the war against Scythian invaders of Illyricum in 268 AD – see below – remarked that he was: ... a man of great experience in military affairs.
This indicates that, whatever his beginnings, he had not only survived involvement in the almost incessant warfare that was the condition of a soldier serving in the Illyrician garrisons in the middle decades of the Third Century, but also that he thereby distinguished himself and that by the mid-260s he had achieved equestrian status and had been singled out for promotion to the most senior commands.
Progression to more senior commands by way of a tour of duty in the units of the Roman garrison (sometimes with successive postings to the Vigiles, the Cohortes Urbanae and the Praetorian Guard) and admission to the ranks of the Protectores Augusti Nostri was a career-path followed by a number of Marcianus's eminent near-contemporaries.
[20] His recorded military exploits in this capacity all relate to campaigns undertaken against incursions of barbarian war-bands from the region to the north of the Black Sea known to the Romans as Scythia in the period 267–69 AD.
However, somewhere in Illyricum they were intercepted by the Imperial field-army under Gallienus which won a substantial victory in the valley of the River Nestos (which marked the border between the provinciae of Macedonia and Thracia) persuading the war-leader of the "Heruli", Naulobatus, to make peace with the Emperor.
[28] Furthermore, it is inferred that, whereas "Gothic" bandsescaped Marcianus after he had chastised them... Claudius fared rather better in the SHA account... hoping to prevent what actually came to pass [i.e. the necessity for a major campaign against Scythian invaders] (he) had not allowed [them] to break forth.
Probably shortly after the Battle of the Nestos Gallienus found it necessary to abandon his operations in Illyricum and hurry back to Italy to crush Aureolus who had risen in revolt and seized Mediolanium (Milan).
[33] The title accorded Marcianus on the Philippopolis Inscription, doux kai strateletes, is interpreted by Gerov to mean that, whereas he had been a dux while Gallienus was in command in Illyricum, he was promoted above that rank when the Emperor left him in charge of the war against the Scythians after his own departure to fight Aureolus.
[34] Gerov further argues that as strateletes Marcianus's command had a territorial significance in that he was made a Praeses, probably of the two Moesias, provinces which lay athwart the main invasion-route for barbarian incursions from the Black Sea.
However, the phrase is interpreted, it seems likely that Town-Council and Citizens of Philippopolis intended it to be known that Marcianus was in supreme command of the force that had saved their city at its moment of greatest peril and that his only superior was Gallienus:... Our August and Unvanquished Lord...
The presently preferred narrative of this war arguing for a second wave of incursions whose ultimate defeat was only achieved by a supreme effort of the Imperial field-army under the Emperor Claudius in bloody confrontations at the Battle of Naissus and in the central Balkans mountains seems to indicate that Marcianus as Gallienus's theatre-commander had had to fight a difficult campaign where successes were accompanied by reversals.
According to Gerov, Aureolus's stubbornly prolonged defence of the city after his defeat in the field had finally obliged Gallienus to summon Marcianus from Illyricum where that officer commanded the only other substantial force currently at his disposal.
The SHA then goes on to suggest that Marcianus was instrumental in contriving the circumstances of Gallienus's death[39] and, when that was accomplished, that it was he who pacified the army rank-and-file which had been enraged by the murder by arranging for the distribution of a substantial donative to each man from the treasury.
Certainly, he is inclined to accept the account of the SHA as exculpating Claudius who he suggests was the posthumous victim of Zosimus's pagan antipathy to his memory as the proclaimed ancestor of Constantine the Great, the first Christian Emperor.
They argue that that author of that work intended to refute any suggestion that Claudius might have been involved in a treasonable conspiracy against a legitimate Emperor, even one so contemptible as Gallienus, because he was, in fact, guilty of just that.
Nevertheless, his general observation on the matter is highly apposite: [...] while the sources are less than clear about the precise chain of events, they are explicit on a single issue: that most of Gallienus's senior officials wanted him dead.
[46]If Marcianus shared the initial view of the army rank and file and dissented from this sentiment there is no reason to suppose that he attempted to thwart the conspiracy or ever contemplated taking vengeance on those involved.
The ancient sources give no indication as to the role of Marcianus in the great war against the "Goths" and related barbarian peoples that culminated in the Roman victories at the Battle of Naissus and, afterwards, in the Balkan mountains – Haemus Mons.
However, the inscriptions from Termessoss and Kibyra (epigraphic sources 2 and 3 above) suggest that he was associated with a campaign to clear the Eastern Mediterranean of "Gothic" pirates who had been ravaging the islands and the southern Anatolian coast since their original incursion from the Black Sea in 267 AD.
Control of Termessos and Kibyra together with that of Sagalassos, a third city where evidence of activity at the time of Claudius II is particularly noted by Biagi, would have been key to the maintenance of Rome's strategic interests in the region.